Orsdxy

What are plausible reasons for equipping an army with the Faceless Goon style helmets? Is there a good reason at all? Please note that its a faceless helmet not a Balaclava or other form of covering but a full on total head covering helmet.

Some examples-

Anonymous

You can see Riot police covering their faces and name tags so to avoid public persecution, the same thing could happen for soldiers if they are deployed into a civillian zone and if identified could risk their personal lives or that of their families because of the acts they have to commit.

NBC Protection

Maybe they are operating a zone of nuclear, biological, or chemical dangers, so the full helmet is needed to protect them from dangers of their enviroment. In this case their uniforms would be completely sealed to prevent contamination.

The very first people to consider that were probably the ancient persians:

Herodotus describes the 'Immortals' as being heavy infantry, led by Hydarnes, it provided the professional corps of the Persian armies and was kept constantly at a strength of exactly 10,000 men. He stated that the unit's name stemmed from the custom that every killed, seriously wounded, or sick member was immediately replaced with a new one, maintaining the corps as a cohesive entity with a constant strength.

Suppose one of your faceless soldiers.gets shot by the enemy and leaves the enemy's sight. Another faceless soldier then engages and gets shot, and again gets replaced. Over time your enemies will be questioning whether they are actually scoring hits, or whether it is even possible to take down that resilient guy. This can reduce enemy morale.

Also what Sasha said.

faceless helmets could be handy for morale purposes in combat. If a faceless ally gets killed next to you it could be less traumatic than seeing the guy you trained with killed. On a similar line of thought bringing faceless soldiers back off the battlefield for medical attention may help to ensure there isn't any preferential treatment.

Faceless helmets could also have an intimidation factor in combat as the helmets give them a less than human appearance, essentially fooling enemies that they have less mercy than a regular soldier or to imagine how horrifying they must be if they need to hide their faces.

source
1. You can have actors who are easy on the eye and can deliver their lines in the native language of your audience. Then with the helmet on you can have fight scenes with a martial arts expert who looks nothing like your actor but who has got sweet martial arts skills. And you can use those same helmeted fight scenes for versions of your program with completely different actors / languages.

2. If actor stops showing up or holds out for more money midseason, you can have his character's helmet get inexplicably stuck on his head and film the rest of the season with someone more tractable.

Full Face protection

A full helmet provides protection not just to the head, but to the eyes and face as well.

NBC

Per Sasha's answer, NBC (Nuclear, Biological, Chemical) protection requires a completely sealed suit, including enclosed head gear.

Harsh environments

Sandstorms, underwater, vacuum, etc.

HUD

At least one of the images you show are from near future style games/movies. Integrated comms, heads up displays, and low-light/enhanced optics make such a device useful for obvious reasons.

Psychology

Intimidation, anonymity, uniformity, and so on, all have a value in some situations.

Other

In general, the helmet, due to general bulk and inconvenience (can't scratch an itch, stuffy, etc) probably won't be worn at all times, likely only being donned just prior to action, similar to current military helmets. And for scenarios where they aren't needed, lighter headgear might be provided. But there will certainly be scenarios where the fully enclosed helmet is useful, if not critical.

Additionally, people are wired to pick out faces. A shiny helmet might not help, but something matte or camouflaged could make it slightly harder to pick out targets, giving a fraction of a second or longer delay that the helmeted soldier could exploit.

And, hey, it looks bad-ass.